Magnetron plasma apparatus

ABSTRACT

A magnetron plasma apparatus boosted by hollow cathode plasma includes at least one electrically connected pair of a first hollow cathode plate and a second hollow cathode plate placed opposite to each other at a separation distance of at least 0.1 mm and having an opening following an outer edge of a sputter erosion zone on a magnetron target so that a magnetron magnetic field forms a perpendicular magnetic component inside a hollow cathode slit between plates and, wherein the plates and are connected to a first electric power generator together with the magnetron target to generate a magnetically enhanced hollow cathode plasma in at least one of a first working gas distributed in the hollow cathode slit and a second working gas admitted outside the slit in contact with a magnetron plasma generated in at least one of the first working gas and the second working gas.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.61/779,597, filed Mar. 13, 2013, the disclosure of which is herebyincorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

The hollow cathode effect and related high-density hollow cathode plasmawas invented in 1916 by F. Paschen in his spectroscopy study of theplasma emission. Hollow forms of his electrodes (short rectangulartubes) for igniting the plasma led to considerably more light intensitythan in simple planar electrodes at the same direct current (dc) power.Later studies showed that the principle of this intense discharge isbased on geometry of the hollow electrode, where electrons emitted fromone cathode wall interact with an equivalent electric field withopposite orientation at the opposite inner wall. Depending on gaspressure and distance between electrode walls the electrons canoscillate between inner walls and enhance substantially the ionizationof the present gas or vapor. Such ionization based on pendulum motion ofelectrons is recognized in the literature as “hollow cathode effect” (P.F. Little et al. 1954). The hollow cathode effect can work also inhollow electrode powered by an alternating current (ac). Typicalfrequency of ac generators for such purpose is between 105 s−1 and 108s−1, i.e. including the radio frequency (rf) range. The first rf hollowcathode was described in U.S. Pat. No. 4,521,286 to C. M. Horwitz. Itwas also found that the anode in the rf hollow cathodes is the plasmaitself (a “virtual anode”) in contact with the counter electrode (L.Bárdos et al. 1988). The hollow cathode effect can be generated also bypulsed dc power.

The hollow cathode effect is not generated in all negatively biasedhollow electrodes. A hollow electrode can differ substantially from realhollow cathodes unless its geometry is optimized to enhance the gasionization inside its hollow part by 1-3 orders of magnitude due to thehollow cathode effect. For example, a large-diameter cylindricalelectrode where the space-charge sheath thickness is much smaller thanthe electrode diameter cannot serve as a hollow cathode. Even at lowergas pressures when the sheath is wider, the effect may not take placedue to a low number of ionizing collisions. In order to excite thiseffect at higher pressures, the distance between walls must be reduceddue to short mean free paths of electrons. The distance d betweenopposite walls of the hollow cathode must be at least twice thethickness of the space charge sheath, which depends on the gas pressurep, but also on the frequency and power of the generator used. Moreover,the gas pressure p inside the hollow cathode is typically higher thanoutside the hollow cathode due to higher temperature caused by the highdensity plasma inside the hollow cathode and due to a pressure gradientformed in the flowing gas or by evaporated cathode material. Also,presence of magnetic fields can affect the confinement and properties ofthe hollow cathode plasma. Therefore, different published empiricalformulas for estimations of the optimal product p·d for the hollowcathode effect in in de hollow cathodes are generally not very useful.

A number of patents and publications describe so-called “hollow cathodemagnetron sputtering” in systems having targets with hollow geometry,mostly cylinder. The target is always negative in order to attract ionsfor bombarding and sputtering, hence the term “hollow cathode target”and “hollow cathode magnetron”. However, without the hollow cathodeeffect, e.g. in large diameter targets or in magnetic fields parallelwith the walls of the target where electrons are deflected from theiroscillations, such systems are not real hollow cathodes. For example, inU.S. Pat. No. 4,966,677 to H. Aichert et al. a magnetron sputteringapparatus has a hollow cathode target with a cathode base in which ahollow target with cylindrical sputtering surface and cylindrical outersurface is disposed. Neither the parallel magnetic field with the targetnor the target geometry allows for the hollow cathode effect. Similarly,in U.S. Pat. No. 5,437,778 to V. L. Hedgcoth, a magnetron sputteringsystem comprises a hollow longitudinal cathode that is either made fromor has its interior wall coated with a material to be sputtered. Nohollow cathode effect can be excited in such systems. Similarly, in U.S.Pat. No. 6,283,357 to S. Kulkarni et al. a plate of sputter targetmaterial is bonded to a sheet of cladding material and then formed intoa “hollow cathode” magnetron target. In U.S. Pat. No. 6,887,356 to R. B.Ford et al. a sputtering target is claimed preferably exhibiting uniformgrain structure and texture at least on the sidewalls thereof, but nohollow cathode effect is utilized. Another example is PCT Publication WO2007/130903 to J. K. Kardokus et al., where methods of forming “hollowcathode” magnetron sputtering targets are claimed. In these targets, ametallic material is processed to produce an average grain size of lessthan or equal to about 30 microns. Such sputtering target preferablyexhibits substantially uniform sputtering erosion, but no hollow cathodeeffect is utilized. Basic principles of these so-called “hollow cathodemagnetrons” are explained e.g. by D. A. Glocker (SVC TechnicalConference Proceedings 1995).

Since its discovery in 1974 in U.S. Pat. No. 4,166,018 to J. S. Chapin(later described by P. S. McLeod et al. 1977 and R. K. Waits 1978), themagnetron sputtering device underwent a number of improvements aimedmainly to (i) an increase of the target utilization, (ii) a possibilityto sputter magnetic targets, (iii) an increase of an ion flux to thesubstrate, (iv) an increase of the sputtering rate, (v) an increase ofthe ionization level in the whole magnetron plasma. Substantial progressin tasks (i) and (ii) has been obtained by optimizing geometry andinduction of the magnetic tunnels for plasma confinement, particularlyby strong permanent magnets, but also by using hollow targets asexplained above. Such efforts also included different systems withmoving magnets and culminated in an arrangement for target utilizationbased on a rotating cylindrical target (U.S. Pat. No. 4,356,073 to H. E.McKelvey, filed 1981, and a number of later patents e.g., U.S. PatentPublication 2009/0260983 to M. A. Bernick, filed in 2009). Aconsiderable advance in task (iii) was obtained by partial opening ofthe magnetic tunnel from so-called “closed field magnetrons” toso-called “unbalanced magnetrons” (B. Window et al. 1986). This solutionallows for an enhanced presence of ions (plasma) close to the substrate,efficient biasing of the substrates and controlled growth of e.g. veryhard films and special film textures. It is noteworthy that so far theprogress in task (iv), i.e. in increasing the sputtering rates, has beenobtained by increasing target erosion areas, while different arcevaporators rather than any sputtering devices continued to be reliedupon as the fastest physical vapor deposition (PVD) systems. An increasein the ionization of the magnetron plasma (task (v)) can obviouslyincrease the sputtering rate, such as, for example through additionalionization by an rf coil (S. M. Rossnagel et al., 1993). However, recenttrends are focused rather to high power impulse magnetron sputtering(HiPIMS) systems disclosed in U.S. Pat. No. 6,296,742 to Kouznetsov(filed in 1997), where the high power peaks increase the ionizationdramatically. However due to the pulsed power regime, the averagecoating rate barely reaches rates comparable to conventional dcmagnetrons. Thus, the advantage of favorable coating propertiesavailable in high-density plasma of HiPIMS is outweighed by thenecessity of complicated and expensive pulsed power generators and sofar also by an unimpressive deposition rates.

A direct method of increasing the sputtering rate by increasing theionization in the magnetron plasma using the hollow cathode has beenpatented by J. J. Cuomo et al. in May 1986 in U.S. Pat. No. 4,588,490“Hollow cathode enhanced magnetron sputtering device”. Cuomo et al.combine a hollow cathode as an electron-emitting device with a plasmasputter etching/deposition device such as a magnetron. The hollowcathode is utilized to provide additional ionization of the working gasduring magnetron operation and can provide main ionization of theworking gas at low magnetron powers. The hollow cathode utilizesthermionic electron emission to inject electrons. For this purpose, itcomprises a hollow tubular member constructed of a refractory metal anda plurality of layers of electron emissive foils. The hollow cathode ispowered by a de power source independent on the magnetron powergenerator. In the preferred configuration, the axis of the cylindricalhollow cathode is parallel with the planar magnetron target andpositioned above the target close to its edge. In order not to impedethe magnetron drift current the radial position of the hollow cathodemust be such that the magnetic field lines that it intersects travel tothe center pole, rather than the bottom of the magnetic assembly. Thusthe patent discloses an application of a thermionic hollow cathodeemitting electrons, without electrical or physical impediment of themagnetron drift current, but also without magnetic enhancement of thehollow cathode plasma. The cathode should be fabricated from refractorymetals (e.g. Ta). Low-pressure thermionic regimes of the hollow cathodeallow for about 10-times lowering of the magnetron operation pressure,i.e. down to 4-6.7×10-2 Pa (0.3-0.5 mTorr). This type of use of the hothollow cathode arcs as an auxiliary ionizer in magnetrons is describedin the literature as “magnetrons with additional gas ionization” (J.Musil et al., 2006, p. 71-72). An important requirement in suchprocesses is that the cathode metal should not be released and mixedwith the sputtered material from the magnetron target.

Another way for involving the hollow cathode plasma in the magnetrondischarge is formation of grooves or bores directly in the target inorder to excite the hollow cathode effect inside these grooves or bores(J. Musil et al., 2006, pp. 91-93). Such arrangements decrease thenecessary voltage for the magnetron discharge, but the sputtering ratedecreases as well. Moreover, the targets have rather complicated formsand as the target is consumed during magnetron operation the depths ofsuch hollow cathodes are reduced, requiring changes in power parameters.

In addition to their ability to generate very high-density plasmas(comparable to HiPIMS), due to the hollow cathode effect, hollowcathodes can be used for both ion sputtering and are evaporation wherethe cathode itself is a PVD target. Besides dc power, the hollowcathodes can be advantageously powered by pulsed dc or ac electric power(up to the rf range), and can be used to activate gases for fastplasma-enhanced chemical vapor deposition (PE CVD) regimes. Shapes anddimensions of the cathodes can be designed for a wide range of workinggas pressures from about 1.33×10² Pa (10¹ Torr) up to atmospheric andhigher pressures. Besides conventional tube shaped cathodes, thependulum motion of electrons can also occur between parallel conductive“plates” (with rf power even when plates are coated by dielectrics) toproduce dense hollow cathode plasma. Moreover, the hollow cathode effectcan be enhanced and focused in selected areas (hot zones) by suitablemagnetic fields, as disclosed in U.S. Pat. No. 5,908,602 to L. Bárdos etal. (1994). Main part of the magnetic induction lines (induction vectorB) in the slit between parallel linear plates of the hollow cathodesshould be perpendicular to the cathode plates in order not to deflectelectrons and prevent their oscillations between opposite walls.Electrons moving along vector B are not affected by the magnetic force.However, because the vector E of the electric field in the power circuitis oriented towards the anode, i.e. out of the slit, a considerabledisadvantage of the static magnetic field is the tendency to force theplasma to one side of the slit depending on the orientation of magneticinduction vector B. The drift velocity of electrons is given be thevector product (E×B)/B² (E is the vector of electric field perpendicularto a magnetic induction vector B). The drift velocity vector isperpendicular to both vectors E and B. This insufficiency can becompensated in apparatuses having rotating magnets, as disclosed in U.S.Pat. No. 6,351,075 to H. Baránková et al., where magnetic inductionvector B across the hollow cathode slit is changed in both itsorientation and amplitude. An obvious disadvantage of such apparatusesis the necessity of mechanical means for driving the magnets.

SUMMARY OF THE INVENTION

An object of the present invention is therefore to overcome the abovedescribed drawbacks and to provide magnetron devices boosted bymagnetically enhanced dense hollow cathode plasma generated in aparallel-plate hollow cathode placed inside the magnetic field of themagnetron for supplying a dense plasma into the magnetron plasma forsubstrate processing.

The invention provides a magnetron plasma apparatus boosted by hollowcathode plasma for plasma processing on a substrate in a reactor,comprising a parallel plate hollow cathode with a slit wherein a hollowcathode effect can be excited, a magnetron sputtering apparatus with amagnetron target, an electric power generator for generation of plasmaand a magnetic system generating a magnetron magnetic field giving formto an erosion zone on the magnetron target surface and spatial shape ofthe magnetron plasma.

A first aspect of the invention provides a magnetron plasma apparatusboosted by hollow cathode plasma for plasma processing wherein at leastone electrically connected pair of a first hollow cathode plate and asecond hollow cathode plate placed opposite to each other at aseparation distance of at least 0.1 mm has an opening following an outeredge of a sputter erosion zone on a magnetron target so that a magnetronmagnetic field forms a perpendicular magnetic induction component insidea hollow cathode slit between said first and second plate. Said pair ofplates is connected to a first electric power generator together withsaid magnetron target to generate a magnetically enhanced hollow cathodeplasma in at least one of a first working gas distributed in said hollowcathode slit and a second working gas admitted outside said slit incontact with a magnetron plasma generated in at least one of said firstworking gas and said second working gas.

A second aspect of the invention relates to a magnetron plasma apparatusboosted by hollow cathode plasma for plasma processing wherein saidsecond hollow cathode plate is integrated in said magnetron target andsaid hollow cathode slit where said hollow cathode plasma is formed iscreated between said first hollow cathode plate and said magnetrontarget.

A third aspect of the invention relates to a magnetron plasma apparatusboosted by hollow cathode plasma for plasma processing wherein said pairof said first hollow cathode plate and said second hollow cathode plateare electrically insulated from said magnetron target and connected to asecond electric power generator.

A fourth aspect of the invention relates to a magnetron plasma apparatusboosted by hollow cathode plasma for plasma processing wherein saidmagnetically enhanced hollow cathode plasma inside said hollow cathodeslit forms a first hot zone on said first cathode plate and a second hotzone on said second hollow cathode plate and said first and second hotzones evaporate material from said first and second hollow cathodeplates.

A fifth aspect of the invention relates to a magnetron plasma apparatusboosted by hollow cathode plasma for plasma processing wherein saidmagnetron target has cylindrical form in a rotatable target magnetronapparatus and said pair of said first hollow cathode plate and saidsecond hollow cathode plate are mechanically decoupled from saidmagnetron target.

A sixth aspect of the invention relates to a magnetron plasma apparatusboosted by hollow cathode plasma for plasma processing wherein multiplepairs of said first hollow cathode plate and said second hollow cathodeplate have annular circular openings and create a hollow cylindricalshape of said magnetron target.

A seventh aspect of the invention relates to a magnetron plasmaapparatus boosted by hollow cathode plasma for plasma processing whereinat least one of said first hollow cathode plate, said second hollowcathode plate and said magnetron target is fabricated at least in somepart from a different material.

An eighth aspect of the invention relates to a magnetron plasmaapparatus boosted by hollow cathode plasma for plasma processing whereinsaid individual pairs of said first and second hollow cathode plates areout of parallel with each other or with respect to said magnetrontarget.

A ninth aspect of the invention relates to a magnetron plasma apparatusboosted by hollow cathode plasma for plasma processing wherein saidfirst hollow cathode plate and said second hollow cathode plate haveother than planar shapes and compose uneven forms of said hollow cathodeslit.

A tenth aspect of the invention relates to a magnetron plasma apparatusboosted by hollow cathode plasma for plasma processing, wherein saidmagnetically enhanced hollow cathode plasma is generated in said firstworking gas.

Other goals and advantages of the invention will be further understoodand appreciated in conjunction with the following description andaccompanying drawings. While the following description may containspecific details describing particular embodiments of the invention,this should not be construed as limitations to the scope of theinvention but rather as an exemplification of preferable embodiments.For each aspect of the invention, many variations are possible assuggested herein that are known to those of ordinary skill in the art. Avariety of changes and modifications can be made within the scope of theinvention without departing from the spirit thereof.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

-   F. Paschen, “2. Bohrs Heliumlinien”, Annalen der Physik,    IV (50) (1916) 901.-   P. F. Little and A. vonEngel, “The hollow-cathode effect and the    theory of glow discharges”, Proc. Royal Society London, A224 (1954)    209-227.-   U.S. Pat. No. 4,521,286 “Hollow cathode sputter etcher” filed    by C. M. Horwitz in March 1984.-   L. Bárdos and V. Dusek, “High rate jet plasma-assisted chemical    vapour deposition”, Thin Solid Films 158 (1988)265-270.-   U.S. Pat. No. 4,966,677 “Cathode sputtering apparatus on the    magnetron principle with a hollow cathode and a cylindrical target”    filed by H. Aichert et al. in April 1989.-   U.S. Pat. No. 5,437,778 “Slotted cylindrical hollow    cathode/magnetron sputtering device” filed by V. L. Hedgcoth in    November 1993.-   U.S. Pat. No. 6,283,357 “Fabrication of clad hollow cathode    magnetron sputter targets” filed by S. Kulkarni et al. in August    1999-   U.S. Pat. No. 6,887,356 “Hollow cathode target and methods of making    same” filed by R. B. Ford et al. in November 2001-   PCT Publication WO 2007/130903 “Hollow cathode magnetron sputtering    targets and methods of forming hollow cathode magnetron sputtering    targets” filed by J. K. Kardokus et al. in May 2006.-   D. A. Glocker, “Principles and Applications of Hollow Cathode    Magnetron Sputtering Sources”, 38th Annual SVC Technical Conference    Proceedings (1995), pp. 298-302, ISSN 0737-5921.-   U.S. Pat. No. 4,166,018 “Sputtering process and apparatus” filed    by J. S. Chapin in January 1974.-   P. S. McLeod and L. D. Hartsough, “High rate sputtering of aluminum    for metallization of integrated circuits”, J. Vac. Sci. Technol.    14 (1) (1977) 263-265.-   R. K. Waits, “Planar magnetron sputtering”, J. Vac. Sci. Technol. 15    (2)(1978) 179-187.-   U.S. Pat. No. 4,356,073 “Magnetron cathode sputtering apparatus”    filed by H. E. McKelvey in February 1981.-   U.S. Patent Publication 2009/0260983 “Cylindrical magnetron” filed    by M. A. Bernick in April 2009.-   B. Window and N. Savvides, “Charged particle fluxes from planar    magnetron sputtering sources”, J. Vac. Sci. Technol. A4 (2) (1986)    196-202.-   S. M. Rossnagel and J. Hopwood, “Magnetron sputter deposition with    high levels of metal ionization”, Appl. Phys. Letters 63 (1993)    3285-3287.-   U.S. Pat. No. 6,296,742 “Method and apparatus for magnetically    enhanced sputtering”, filed by V. Kouznetsov in December 1997.-   U.S. Pat. No. 4,588,490 “Hollow cathode enhanced magnetron    sputtering device” filed by J. J. Cuomo et al. in May 1986-   J. Musil, J. Vlcek and P. Baroch, “Magnetron discharges for thin    films plasma processing”, Chapter 3, pp. 67-110, in “Materials    Surface Processing by Directed Energy Techniques”, ed. by Yves    Pauleau, EMRS Book Series, Elsevier, 2006-   U.S. Pat. No. 5,908,602 “Apparatus for generation of a linear arc    discharge for plasma processing”, filed by L. Bárdos and H.    Baránková, priority November 1994.-   U.S. Pat. No. 6,351,075 “Plasma processing apparatus having rotating    magnets”, filed by H. Baránková and L. Bárdos, priority November    1997.

BRIEF DESCRIPTION OF THE DRAWING(S)

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIG. 1 is a schematic view of a first embodiment and explanation of asecond embodiment according to the present invention showing an exampleof magnetron plasma apparatus boosted by hollow cathode plasma forplasma processing on a substrate in a reactor at gas pressure below6.65×103 Pa (50 Torr).

FIG. 2 is a view of magnetized hollow cathode plasma generated bydifferent parallel-plate hollow cathodes in a perpendicular magneticfield explaining preferred embodiments according to the presentinvention.

FIG. 3 is a schematic view of an example of third embodiment accordingto the present invention, where the parallel plate hollow cathode iselectrically insulated from the magnetron target.

FIG. 4 is a schematic view of an example of a fourth embodimentaccording to the present invention, where the magnetron target hascylindrical form in a rotatable target magnetron apparatus.

FIG. 5 is a schematic view of an example of a fifth embodiment accordingto the present invention, where multiple pairs of hollow cathode platescreate a hollow cylindrical magnetron target.

FIG. 6 is a schematic view of two examples of another alternativesaccording to the present invention, where hollow cathode plates are notin parallel with each other and/or with the magnetron target.

DESCRIPTION OF THE INVENTION

Throughout the drawings, the same reference numbers are used for similaror corresponding elements.

The invention provides systems and methods for the plasma processing onsubstrates, such as, for example sputtering and dry etching. Theinvention provides also systems and methods with contribution of areevaporation and/or sputtering of the hollow cathode plate material intothe magnetron plasma and for processing on the substrates. Ionized andactivated particles in the apparatus according to this invention can beused in various regimes for ion plating, activated reactive evaporation,reactive sputtering, evaporation and combined regimes, etc. It ispossible to utilize direct processes incorporating sputtered andevaporated materials from magnetron target and from hollow cathodeplates with or without an inert working gas, as well as reactiveprocesses incorporating chemical reactions of these materials withactivated reactive working gases, different chemical precursors, vapors,etc. Various aspects of the invention described herein may be applied toany of the particular applications set forth below or in any other typeof plasma processing including, but not limited to combinations ofseveral apparatuses according to this invention, or combinations withother types of plasma systems, like microwave plasma systems, arcevaporators, laser plasma sources, etc. It shall be also understood thatdifferent aspects of the invention can be appreciated individually,collectively, or in combination with each other.

Referring to FIG. 1, a first embodiment of a magnetron plasma apparatusboosted by hollow cathode plasma for plasma processing on a substrate ina reactor according to the present invention will be described. Inpractically implemented embodiments gas pressures below about 6.65×103Pa (50 Torr) can be used. In the present embodiment, at least oneelectrically connected pair of a first hollow cathode plate 1 and asecond hollow cathode plate 2 placed parallel and opposite to each otherat a separation distance of 0.5 mm between them has an opening along anouter edge of a sputter erosion zone 3 on a magnetron target 4. Theseparation of 0.5 mm is considered as a typical practical lowest limit,even if separation distances down to about 0.1 mm would be possible tomake the apparatus operable. The pair of cathode plates is placed sothat a magnetron magnetic field 5 forms a perpendicular magneticinduction component 6, in this embodiment of at least 10-2 Tesla, insidea hollow cathode slit 7 between plates 1 and 2, and the pair of plates 1and 2 is electrically connected to a first electric power generator 8together with target 4 to generate a magnetically enhanced hollowcathode plasma 9 in a first working gas 10 distributed in the hollowcathode slit 7 in contact with a magnetron plasma 11 generated in thefirst working gas 10 and in a second working gas 12 admitted outsideslit 7. Thus the apparatus according to the present embodiment utilizesthe magnetic field 5 of the magnetron for generation of the magneticallyenhanced hollow cathode plasma 9 inside slit 7. For further improvedperformance of the magnetically enhanced hollow cathode plasma 9 thedepth of the slit 7 given by the widths of plate 1 and plate 2 should beat least of twice the distance between plate 1 and 2. The magnetronmagnetic field 5 can have different shapes. A typical tunnel-shaped partof the field confines in the present embodiment the plasma above thetarget and defines the shape of the sputter erosion zone 3 on the target4. The magnetic induction at the outer edge of the erosion zone 3 isclose to one pole of a magnetron magnetic system 17 and can in thepresent embodiment generate the perpendicular magnetic inductioncomponent 6 of at least 10-2 Tesla inside the hollow cathode slit 7 toform the magnetically enhanced hollow cathode plasma 9. In so-calledunbalanced magnetrons, the magnetic system 17 contains also means forpartial unbalancing of the tunnel magnetic field to allow more ions toescape the magnetic tunnel and travel to a substrate 19. The unbalancingof the field can be provided also without use of the additional means bypositioning of magnets in the system 17 under the target 4. Depending onpower of the electric generator 8, an ion bombardment inside the hollowcathode slit 7 from the magnetically enhanced hollow cathode plasma canform first and second hot zones 14 and 15 at respective cathode plates 1and 2. The temperature of the respective hot zones depends on thecooling effect from the magnetron target, thickness of the respectiveplates, as well as on the thermal conductivity of the plates. Therefore,in various embodiments, the hot zone 15 at the second plate 2 at themagnetron target can acquire lower temperature than the first hot zone14 at the first plate 1. The magnetically enhanced hollow cathode plasma9 expands from the slit 7 and interacts with the magnetron plasma 11 tocompose a resulting processing plasma 18 that can contain at least oneof ionized material of the magnetron target 4, ionized first working gas10, ionized second working gas 12 and ionized sputtered and/orevaporated material particles from the hollow cathode plates 1 and 2. Indifferent embodiment, the resulting processing plasma can contain anycombination or subset of these components. In a typical embodiment, theresulting processing plasma 18 comprises ionized material of themagnetron target 4, ionized first working gas 10 and ionized secondworking gas 12. In the particular embodiment of FIG. 1, the magneticallyenhanced hollow cathode plasma ca be generated in the first working gas.In other embodiments, the magnetically enhanced hollow cathode plasma isgenerated in the second working gas. The working gases may also indifferent embodiment be composed from several components. In a typicalembodiment, the first hollow cathode plate 1, the second hollow cathodeplate 2 and the magnetron target 4 can be fabricated in the samematerial. However, in other embodiments, at least one of the firsthollow cathode plate 1, the second hollow cathode plate 2 and themagnetron target 4 can be fabricated at least in some part from adifferent material. In other words, the first hollow cathode plate 1,the second hollow cathode plate 2 and/or the magnetron target 4 may becomposed of parts of different materials, or one or two of the firsthollow cathode plate 1, the second hollow cathode plate 2 and/or themagnetron target 4 may be composed of a different material compared tothe other ones. In such a way, different compositions of the resultingprocessing plasma 18 can be achieved. Thus the processing plasma 18contains high density of ions for plasma processing on the substrate 19.If suitable in a simple modification of the first embodiment in FIG. 1(not shown) the second hollow cathode plate 2 can be integrated directlyinto the magnetron target 4. However in many practical cases the secondhollow cathode plate 2 can be used for a mechanical holding of themagnetron target 4 on a cooled holder (not shown) of the target 4. Insuch embodiments, there is a direct mechanical attachment between thesecond hollow cathode plate 2 and the target 4.

FIG. 2 is a view of magnetized hollow cathode plasma generated bydifferent parallel-plate hollow cathodes in a perpendicular magneticfield. It is shown that the perpendicular magnetic induction component 6in a slit 7 of a parallel-plate hollow cathode composed of plate 1(shown in a semi-transparent manner) and plate 2, described for examplein U.S. Pat. Nos. 5,908,602 and 6,351,075, causes side drifts of themagnetically enhanced hollow cathode plasma 9 depending on orientationof the component 6. If the plates form a closed circumferential shape ofthe hollow cathode slit 7 the magnetically enhanced hollow cathodeplasma 9 has a uniform circumferential shape independent on orientationof the perpendicular component 6, e.g. shape of a circle or a racetrack,as shown in FIG. 2. This property allows for utilization of themagnetron magnetic field 5 and incorporation of these circumferentialparallel-plate hollow cathodes with the magnetron target 4 according tothe present invention, as shown in FIG. 1. Thus the apparatus accordingto the invention can be applied to arbitrary forms of the planarmagnetrons (circular, rectangular triangular, polygonal, etc.).

Examples

Referring to FIG. 3, a schematic view of an example of a thirdembodiment according to the present invention is explained. In thisembodiment, at least one electrically connected pair of the first hollowcathode plate 1 and the second hollow cathode plate 2 is electricallyinsulated from the magnetron target 4, for example by an insulator 20.Plates 1 and 2 are placed opposite to each other at a separationdistance of at least 0.5 mm and have an opening following an outer edgeof the sputter erosion zone 3 on a magnetron target 4 so that themagnetron magnetic field 5 forms a perpendicular magnetic inductioncomponent 6 of at least 10-2 Tesla inside a hollow cathode slit 7between plates 1 and 2. The plates 1 and 2 are electrically connected toa second electric power generator 13 independent from the first electricpower generator 8 powering the magnetron target 4. The magneticallyenhanced hollow cathode plasma 9 is generated in a first working gas 10distributed in the hollow cathode slit 7 in contact with a magnetronplasma 11 generated in the first working gas 10 and in a second workinggas 12 admitted outside slit 7. Generator 13 supplies enough power foran ion bombardment inside the hollow cathode slit 7 by the magneticallyenhanced hollow cathode plasma 9 which forms first and second hot zones14 and 15 at respective cathode plates 1 and 2. An advantage of thisembodiment is an independent control of the magnetron plasma 11 and themagnetically enhanced hollow cathode plasma 9 and consequentlyrespective yields of sputtered and evaporated materials in the resultingprocessing plasma 18 at the substrate 19.

Referring to FIG. 4, a schematic view of an example of a fourthembodiment according to the present invention is explained. In thisembodiment the magnetron target 4 has cylindrical form in a rotatabletarget magnetron apparatus and the pair of the first hollow cathodeplate 1 and second hollow cathode plate 2 is mechanically decoupled fromrotating magnetron target 4. In this embodiment, the magneticallyenhanced hollow cathode plasma 9 can be generated by the second electricpower generator 13 independently from the magnetron target 4, but alsotogether with the magnetron target from the same first electric powergenerator 8. In this schematic view all reference numbers are listed inthe LIST OF THE USED REFERENCE NUMBERS below.

Referring to FIG. 5 a schematic view of an example of a fourthembodiment according to the present invention is explained. In thisembodiment multiple pairs of the first hollow cathode plate 1 and secondhollow cathode plate 2 have annular circular openings and create ahollow cylindrical magnetron target 4 wherein the second hollow cathodeplate 2 is the first hollow cathode plate 1 of the adjacent pair ofplates. The target is electrically connected to the first electric powergenerator 8 and is electrically insulated from the anode 16 by aninsulator 20. Anode 16 locks the target and the insulator 20 on thesides by side closures 21. In this embodiment the first working gas 10is distributed into all individual hollow cathode slits 7 by at leastone gas distributor channel 22. A feasible modification of thisembodiment (not shown) is a multiple magnetron target 4 consisting ofmultiple target segments each containing one or more pairs of the firsthollow cathode plate 1 and second hollow cathode plate 2, wherein eachtarget segment is encapsulated in a corresponding segment of theinsulator 20 and locked into a corresponding segment of the anode 16with closures 21. In this modification, a common first electric powergenerator 8 can be used simultaneously in all parallel segments, ormultiple generators can be used for powering of each target segmentseparately. In this embodiment the apparatus is suitable for processingof axially positioned cylindrical or round types of substrate 19. Inthis schematic view all reference numbers are listed in the LIST OF THEUSED REFERENCE NUMBERS below.

Referring to FIG. 6, schematic views of examples of still moreembodiments according to the present invention are explained. In theseexamples, the pairs of plates 1 and 2 are not in parallel with themagnetron target 4 and can form an angle 23 with respect to the target4. Angle 23 can have also an opposite orientation to that shown in FIG.6. Also, hollow cathode plates 1 and 2 may not be positioned in parallelwith each other and can form an angle 24 in both orientations, where thehollow cathode slit 7 is either more opened or more closed towards thetarget 4. The options explained schematically in FIG. 6 can be used indifferent combinations. Another option is that the first hollow cathodeplate 1 and the second hollow cathode plate 2 have other than planarshapes and compose uneven forms of the hollow cathode slit 7. Stillother options are based on different combinations of working gases, aswell as on possibility to operate the magnetically enhanced hollowcathode plasma 9 in the slit 7 without use of the first working gas 10(the inlet of the gas 10 may be closed) and only in the second workinggas 12. Thus the magnetically enhanced hollow cathode plasma 9 and/orthe magnetron plasma 11 can be generated only in the first working gas10 or only in the second working gas 12 where any of the working gases10 and 12 can be composed from several components. In this schematicview all reference numbers are listed in the LIST OF THE USED REFERENCENUMBERS below.

High-density plasmas generated by hollow cathodes in accordance with thepresent invention can advantageously be used in processing proceduresrequiring very dense plasmas, like in the HiPIMS. However, the plasmagenerated by the apparatus according to the present invention bringsmore advantages, for example possibility of high processing anddeposition rates, high activation degree, rapid plasma chemicalreactions and generation of radicals, high rate etching, an improvedstability and control of plasma processes, an efficient control ofproperties of deposited films including new film properties likesuperhard or superelastic films, etc. The plasma processing according tothe present invention enables also different hybrid processes whencombining for example sputtering and evaporation regimes, PE CVD andsputtering and/or evaporation regimes, incorporation of particles fromdifferent materials, deposition of different composite films, etc. Theinvention may offer significant advantages with respect to HiPIMS,including, but not limited to possibility of continuous processing anduse of more simple and cheaper power generators, such as for example dc,pulsed dc, ac and rf. Moreover, as the HiPIMS represents a generationmode of the magnetron plasma rather than the magnetron itself themagnetron plasma apparatus according to the present invention can beused also in HiPIMS regimes. A further advantage of differentembodiments of the apparatus according to this invention is capabilityof operating at relatively high pressures as compared to typicalpressures of 0.13-1.3 Pa (1-10 mTorr) for magnetron sputtering oretching. This is enabled by the magnetically enhanced hollow cathodes,which can work at high pressures and supply high-density plasma into themagnetron. It is necessary, however, to adjust the geometry of thehollow cathode and the whole system, the position of the substrate andthe gas flow rates according to the required gas pressure due todifferences in the mean free paths of plasma particles.

While preferable embodiments of the present invention have been shownand described herein, it will be obvious to those skilled in the artthat such embodiments are provided as an example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. It should be understoodthat various alternatives to the embodiments of the invention describedherein could be employed in practicing the invention. It is intendedthat the following claims define the scope of the invention and thatmethods and structures within the scope of these claims and theirequivalents be covered thereby.

LIST OF THE USED REFERENCE NUMBERS

-   -   1—first cathode plate    -   2—second cathode plate    -   3—sputter erosion zone    -   4—magnetron target    -   5—magnetic field    -   6—perpendicular magnetic induction component    -   7—hollow cathode slit    -   8—first electric power generator    -   9—magnetically enhanced hollow cathode plasma    -   10—first working gas    -   11—magnetron plasma    -   12—second working gas    -   13—second electric power generator    -   14—first hot zone    -   15—second hot zone    -   16—anode    -   17—magnetic system    -   18—processing plasma    -   19—substrate    -   20—insulator    -   21—anode side closures    -   22—gas distributor channel    -   23—angle between hollow cathode plates 1 and 2 and the magnetron        target 4    -   24—angle between cathode plate 1 and 2

1-10. (canceled)
 11. A method of plasma processing, comprising:providing a magnetron sputtering apparatus comprising a magnetron targetand having a magnetron magnetic field giving form to a spatial shape ofa magnetron plasma; providing a hollow cathode comprising anelectrically connected pair of a first hollow cathode plate and a secondhollow cathode plate separated from each other allowing a hollow cathodeeffect to be excited in a slit between said first hollow cathode plateand said second hollow cathode plate, wherein said magnetron magneticfield forms a perpendicular magnetic induction component inside saidslit; and using said perpendicular magnetic induction component insidesaid slit to magnetically enhance a hollow cathode plasma formed by saidhollow cathode.
 12. The method of claim 11, wherein said perpendicularmagnetic induction component inside said slit is parallel to a pendulummotion of electrons in said hollow cathode effect in said hollowcathode.
 13. The method of claim 11, further comprising placing at leastone of said first hollow cathode plate and said second hollow cathodeplate separately from said magnetron target.
 14. The method of claim 11,wherein said magnetron sputtering apparatus is a planar magnetronapparatus.
 15. The method of claim 11, wherein said magnetron sputteringapparatus is a rotatable target magnetron apparatus.
 16. The method ofclaim 11, wherein said first and second hollow cathode plates arediscrete and spaced apart from each other.
 17. The method of claim 11,further comprising using at least two magnets with opposing poles belowsaid magnetron target to generate said magnetron magnetic field.
 18. Themethod of claim 11, wherein said magnetron target is a single-piecemagnetron target.
 19. The method of claim 11, further comprisingconnecting said hollow cathode to a continuous or pulsed powergenerator.
 20. The method of claim 19, further comprising electricallyinsulating said hollow cathode from said magnetron target.
 21. Themethod according to claim 11, further comprising using said plasmaprocessing apparatus for plasma processing on a substrate in a reactor.22. The method according to claim 11, wherein (i) said first and secondhollow cathode plates are out of parallel with each other and/or atleast one of said first and second hollow cathode plates is out ofparallel with respect to said magnetron target, or (ii) said first andsecond hollow cathode plates are parallel with each other.
 23. Themethod according to claim 11, wherein said first hollow cathode plateand said second hollow cathode plate have other than planar shapes andcompose uneven forms of said slit.
 24. The method according to claim 11,further comprising using said first and second hollow cathode plates toform a closed circumferential shape of said slit.
 25. The methodaccording to claim 11, wherein said perpendicular magnetic inductioncomponent inside said slit is at least 10-2 Tesla.
 26. The methodaccording to claim 11, further comprising fabricating at least one ofsaid first hollow cathode plate, said second hollow cathode plate andsaid magnetron target at least in some part from a different material.27. The method according to claim 26, wherein (i) at least one of saidfirst hollow cathode plate and said second hollow cathode platecomprises a different material than said magnetron target, or (ii) saidfirst hollow cathode plate comprises a different material than saidsecond hollow cathode plate.
 28. The method according to claim 11,further comprising mechanically decoupling said pair of said firsthollow cathode plate and said second hollow cathode plate from saidmagnetron target.
 29. The method according to claim 11, furthercomprising integrating said second hollow cathode plate in saidmagnetron target and forming said slit between said first hollow cathodeplate and said magnetron target.
 30. The method according to claim 11,further comprising using said hollow cathode plasma inside said slit toform a first hot zone on said first hollow cathode plate and a secondhot zone on said second hollow cathode plate, and using said first andsecond hot zones to evaporate material from said first and second hollowcathode plates.